This invention relates to an additive for hair growing agent and a hair growing agent composition containing it, more particularly it relates to the additive for hair growing agent composed of a specific silicone-based compound and capable to secure the hair growing effect, even if the content of the pharmaceutically active components is reduced from that of the conventional hair growing agent composition, hence the side-effect thereof could be reduced, and to the hair growing agent composition containing it.
Hair growing agents incorporated with a variety of pharmaceutically active components have been known and widely used to remove or reduce the causes for baldness or loss of hair. However, many of these pharmaceutically active components have potential risk to produce side-effects. For example, minoxidil (2,4-diamino-6-piperidinopyrimidine-3-oxide), which recently has been widely used, is a pharmaceutical originally developed as a remedy for hypertension, and will cause the problem, when used as the hair growing agent, by the antihypertensive action of the minoxidil due to its original pharmaceutical effect.
It is an object of this invention to offer an inexpensive hair growing agent composition which has a low potential of the side-effect by decreasing the content of the pharmaceutically active components, while keeping the sufficient hair growing effect.
The inventors of the present invention have found, after having extensively studied to solve the above problem, that a hair growing agent composition can exhibit a sufficient hair growing action, even when the content of the pharmaceutically active components is decreased, by incorporating a silicone-based compound of the specific structure therein, and this invention has been accomplished basing on the above knowledge.
This invention offers an additive for hair growing agent shown by the following general formula (I): 
wherein, R1 is an alkyl group having a carbon number of 1 to 30, an aryl group or a group shown by the formula (R2)3SiOxe2x80x94 or xe2x80x94YO(C2H4O)a(C3H6O)bR3; at least one of R1s is an alkyl group having a carbon number of 6 to 30 or a group shown by the formula xe2x80x94YO(C2H4O)a(C3H6O)bR3; R2 is an alkyl group having a carbon number of 1 to 5 or an aryl group; R3 is a hydrogen atom, an alkyl group having a carbon number of 1 to 6 or an acetoxy group; Y is a divalent organic group bound to an adjacent silicon atom through a carbon-silicon bond and to a polyoxyalkylene block through an oxygen atom; m is a number of 1 to 50 on the average; and a and b are numbers of 0 to 50 on the average respectively, but they satisfy the relationship a+bxe2x89xa72.
This invention also offers an additive for hair growing agent shown by the following general formula (II): 
wherein, R4 is an alkyl group having a carbon number of 6 to 30 or a group shown by the formula xe2x80x94YO(C2H4O)a(C3H6O)bR3; and R2, R3, Y, a and b are the same as those defined in the general formula (I).
This invention also offers a hair growing agent composition containing a pharmaceutically active component, solvent and the additive for hair growing agent shown by the general formula (I) or (II).
This invention is described more concretely.
The additive for hair growing agent of this invention is a compound shown by the following general formula (I): 
wherein, R1 is an alkyl group having a carbon number of 1 to 30, an aryl group or a group shown by the formula (R2)3SiOxe2x80x94 or xe2x80x94YO(C2H4O)a(C3H6O)bR3; at least one of R1s is an alkyl group having a carbon number of 6 to 30 or a group shown by the formula xe2x80x94YO(C2H4O)a(C3H6O)bR3; R2 is an alkyl group having a carbon number of 1 to 5 or an aryl group; R3 is a hydrogen atom, an alkyl group having a carbon number of 1 to 6 or an acetoxy group; Y is a divalent organic group bound to an adjacent silicon atom through a carbon-silicon bond and to a polyoxyalkylene block through an oxygen atom; m is a number of 1 to 50 on the average; and a and b are numbers of 0 to 50 on the average respectively, but they satisfy the relationship a+bxe2x89xa72.
It is essential that at least one of R1s in the general formula (I) is an alkyl group having a carbon number of 6 to 30 or a group shown by the formula xe2x80x94YO(C2H4O)a(C3H6O)bR3, and the remainder is preferably methyl, ethyl or phenyl group, or a group shown by the formula (R2)3SiOxe2x80x94, more preferably methyl group or a group shown by the formula (CH3)3SiOxe2x80x94.
R2 is an alkyl group having a carbon number of 1 to 5 or an aryl group, preferably an alkyl group having a carbon number of 1 to 3, more preferably methyl group.
R3 is a hydrogen atom, an alkyl group having a carbon number of 1 to 6 or an acetoxy group, preferably a hydrogen atom, or methyl or butyl group.
The preferable examples of Y include xe2x80x94CH2CH2CH2xe2x80x94 and xe2x80x94CH2CH(CH3)CH2xe2x80x94, the former being more preferable.
It is essential that m is a number of 1 to 50 on the average, preferably 1 to 5.
It is essential that a and b are numbers of 0 to 50 on the average respectively and they satisfy the relationship a+bxe2x89xa72, and it is preferable that a is 2 to 20 and b is 0 to 10.
Among the compounds shown by the general formula (I), the particularly preferable one is shown by the following general formula (II): 
wherein, R4 is an alkyl group having a carbon number of 6 to 30 or a group shown by the formula xe2x80x94YO(C2H4O)a(C3H6O)bR3; and R2, R3, Y, a and b are the same as those defined in the general formula (I).
The concrete examples of the preferable compounds include Compounds 1 to 3 shown by the following general formulae: 
When incorporated in a hair growing agent, the additive for hair growing agent of this invention can decrease the content of the pharmaceutically active component. The hair growing agent in which the additive of this invention is incorporated is not limited, and any known one may be used. A hair growing agent generally comprises a pharmaceutically active component, solvent and additives.
The pharmaceutically active components useful for this invention include, vasodilator (e.g., minoxidil, carpronium chloride, benzyl nicotinate, Swertia japonica extract, panax ginseng extract, vitamin E acetate or capsicum tincture), antihistamic agent (diphenhydramine hydrochloride or isothipendyl hydrochloride), antiinflammatory agent (glycyrrhizinic acid or guaiazulene), keratin-dissolving agent (e.g., urea or salicylic acid), antimicrobial agent (chlorhexidine gluconate, isopropyl methylphenol, quarternary ammonium salt, hinokitiol or piroctone olamine), humectant (e.g., sodium hyaluronate or chondroitin sulfate), extracts of various plants or animals (e.g., yew, Paeonia suffruticosa Andrews, Licorice, St. John""s Wort, Aconiti Tuber, Loquat, Artemisia capillaris, comfrey, Angelica keiskei, saffron, gardeniae Fructus, rosemary, sage, Saussurea lappa Clarke, Vladimiria denticulata Ling, hop or placenta), and vitamin (e.g., retinol acetate, pyridoxine hydrochloride, ascorbic acid, thiamine nitrate, cyanocobalamin or biotin).
The solvents useful for this invention include water, alcohols (methanol, ethanol, 2-propanol or denatured ethanol), and cyclosiloxanes (e.g., decamethylcyclopentasiloxane), of which water, ethanol or 2-propanol is preferable.
Other additives useful for this invention include those normally used, such as an antioxidant (e.g., dibutyl hydroxytoluene, sodium pyrosulfite, tocopherol, sodium edetate, ascorbic acid or isopropyl gallate), solubilizer (e.g., diisopropyl adipate, isopropyl myristate, polyethylene glycol, medium chain fatty acid triglyceride, fatty acid ester, various vegetable oils, various animal oils, polyhydric alcohol/fatty acid ester, alkyl glyceryl ether, hydrocarbon, lactic acid or sodium hydroxide), metabolism activator (e.g., panthenol), surfactant (e.g., sorbitan/fatty acid ester, glycerin/fatty acid ester, polyglycerin/fatty acid ester, propylene glycol/fatty acid ester, polyoxyethylene sorbitan/fatty acid ester, polyoxyethylene sorbit/fatty acid ester, polyoxyethylene glycerin/fatty acid ester, polyoxyethylene glycol/fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil, polyoxyethylene beeswax derivative, polyoxyethylene lanolin derivative, polyoxyethylene alkyl amide, polyoxyethylene alkyl amine, lecithin derivative or high-molecular-weight emulsifier), emulsion stabilizer (e.g., higher alcohol), gelling agent (water-soluble high-molecular-weight compound), adhesive, perfume, refrigerant (e.g., menthol, peppermint oil or camphor), or dyestuffs, which may be used within limits where the effect of this invention is not interfered.
The content of the additive for the hair growing agent of this invention is not limited, but preferably it is 0.01 to 2% by weight, more preferably 0.02 to 0.2% by weight, in the hair growing agent composition.
The method for incorporating the additive for the hair growing agent of this invention is not limited, and it may be made by mixing in conventional manners. It may be added to the hair growing agent directly or after being dissolved in a solvent. The solvent may be one described earlier as one of the components for the hair growing agent. The commercial hair growing agent is designed to have a storage stability, and thus the addition of the additive for the hair growing agent of this invention may deteriorate the stability. Therefore, the additive for the hair growing agent of this invention or a solution thereof may be added to the hair growing agent immediately before it is used.
The hair growing agent composition comprising the above-described pharmaceutically active component, solvent, additive for the hair growing agent of this invention, and, as required, one or more other additives is one of the embodiments of this invention.
The content of the pharmaceutically active component varies depending on its type. For example, minoxidil is incorporated preferably at 0.05 to 2% by weight, and carpronium chloride, preferably at 0.25 to 2% by weight. The preferable content of the additive for the hair growing agent of this invention is these range described.
The mechanism of the additive for the hair growing agent of this invention is not fully understood. It is however considered that it easily penetrates into very narrow gaps between the hair roots and hair follicles, which, coupled with the percutaneous absorption from the scalp on which the conventional one depends, allows the additive to directly reach the hair papillas, with the result that the pharmaceutically active component efficiently works on the hair papillas and hence sufficiently exhibits its effect even at the decreased content.